1. Field of the Invention
The present invention relates to an X-ray image reception system executing a resend process in the event of packet loss when using a packet communication network to connect an X-ray imaging device and a display control device. The resend process is executed based on a resend setting determined based on conditions such as an imaging area or an operating method.
2. Description of the Related Art
Generally, an X-ray fluoroscopic imaging apparatus, which performs fluoroscopic imaging in real time for a purpose such as interventional radiology (IVR), includes an X-ray imaging device and a display control device.
In conventional X-ray imaging devices, an analog camera tube or a charge-coupled device (CCD) is connected to an image intensifier and analog data is transmitted to a display control device by video signals for analog display on a monitor.
However, recent advances in the digitalizing of X-ray imaging devices have enabled use of a flat panel sensor (FPD) instead of the analog camera tube or CCD connected to an image intensifier.
In addition, such digitalized systems have been adapted to enable display on a high-resolution monitor via a digital visual interface (DVI) thus enabling construction of a fully digitalized system from imaging to display.
Such a fully digitalized system may use a packet communication network to promote wireless operation, general versatility or compactness of transmission wiring. “Network communication” means communication in which data is separated into small units, and sent or received individually. A piece of separated data is called a “packet”.
A protocol, which can resend data securely, such as Transmission Control Protocol (TCP) is used to send data to the display control device when using a packet communication network. However there are difficulties in increasing the resend data rate due to resend processing.
TCP is a standard internet-based protocol, which forms a reliable connection between the sending-host and the receiving-host processes, to execute resend in the event of data loss. Although TCP is very reliable, its associated transfer efficiency is low. TCP causes large delay in packet arrival resulting in failure of real-time display.
As a result, a User Datagram Protocol (UDP) has been used to reduce delay and enables high-speed transmission. However, UDP entails the risk of packet loss due to the absence of a connection establishment and the transmission of confirmatory responses.
UDP is a standard internet-based protocol, which executes connectionless communication by only sending and receiving data between applications. Its reliability depends on the application. Although UDP has low reliability, its transfer efficiency is high.
Methods including Real-Time Transport Protocol (RTP), which is positioned in a layer above UDP, have been proposed as solutions to the above problems.
An X-ray fluoroscopic imaging apparatus uses an imaging method termed “fluoroscopy” in which a moving image is captured by using low-level X-ray irradiation and the resulting image is not stored, and an imaging method termed “cineradiography” in which a moving image is captured by using high-level X-ray irradiation and the resulting image is stored.
Other imaging methods include a single still image captured using high-level X-ray irradiation, and ROADMAP or Digital Subtraction Angiography (DSA) in which a mask image composed of an average of the first several images is prepared in advance and imaging is executed by using differences of subsequent images with the mask image. Such imaging methods have been applied to various imaging areas including the torso, abdomen, cardiovascular system or the extremities.
Japanese Patent Application Laid open No. 2004-350300 discusses a method in which an error correction method for decoding a compressed image is switched depending on the imaging mode.
However, when packet loss has occurred in sent image data, unique determination of the resend processing of an image is not possible due to the different handling of images during display, storage, printing or transfer after image capture for each of the various imaging areas and imaging methods described above.